1. Field of the Invention
The present invention relates to a vehicle provided with an internal combustion engine that performs fuel-reforming/supplying functions.
2. Description of Related Art
A vehicle is known that includes a conventional fuel reformer e.g., see Japanese Patent Application Laid-open Nos. 52-98819 and 2000-291499.
In the conventional fuel reformer, a reformed fuel is gaseous in most cases, and the amount of a liquid component having a relatively high octane value obtained during a reforming process is relatively small. The gaseous fuel is extremely large in volume compared to a liquid fuel that provides an equivalent amount of heat. As a result, the efficiency of charging the fuel into the internal combustion engine deteriorates, making it difficult to increase the power output from the internal combustion engine. In addition, temporarily storing the gaseous fuel becomes difficult, so that it is difficult to apply the stored gaseous fuel in situations that require a large amount of fuel, such as during vehicle acceleration.
The conventional reformer obtains the heat needed to perform the reforming from an exhaust gas. Accordingly, the conventional reformer disadvantageously provides an unstable reforming reaction because the temperature of the exhaust gas fluctuates extensively depending on the operational state of the internal combustion engine.
Also, a known hybrid vehicle is provided with an internal combustion engine and a vehicle travel motor which uses a fuel cell as a power source.
The known hybrid vehicle suffers from a problem involving a method for supplying hydrogen to the fuel cell. For example, when a high-pressure storage vessel charged with hydrogen is mounted on the vehicle, the number of hydrogen-supply stations are limited because facilities for supplying high-pressure hydrogen are not widespread. Although an attempt has been made to reform hydrocarbon fuel using a steam reforming process and/or a partially oxidizing reaction to produce hydrogen, such reactions disadvantageously require a rather high temperature of 700 to 1,000xc2x0 C., and carbon monoxide contained in the thus-produced hydrogen greatly deteriorates the performance of the fuel cell. For these reasons, a device for removing the carbon monoxide from the produced hydrogen is disadvantageously required, resulting in a complex system.
Further, mounted in a vehicle is a known premixing and compression/ignition-type internal combustion engine in which a mixture comprising an oxygen-containing gas and a fuel is compressed and ignited by itself. In the known premixing and compression/ignition-type internal combustion engine, an extremely lean air-fuel mixture can be burned, and a homogeneous air-fuel mixture is used as a fuel. From this perspective, the known premixing and compression/ignition-type internal combustion engine has attracted public notice as an internal combustion engine that can achieve high burning efficiency and reduce the amount of harmful substances contained in the exhaust gas. In the known premixing and compression/ignition-type internal combustion engine, fuel ignition is conducted by the fuel itself. For this reason, it is difficult to control ignition timing as desired because the fuel self-igniting phenomenon is governed by the chemical reactivity of the fuel and a pressure/temperature rising hysteresis generated by the compression of the air-fuel mixture.
Therefore, there is proposed a method for adjusting the ignition timing by re-circulating a gas which has undergone burning as an intake gas, e.g., see Japanese Patent Application Laid-open No. 6-193447.
However, the method for re-circulating the burned gas as the intake gas suffers from the difficulty of not being able to promptly control ignition timing in accordance with the operational state of the premixing and compression/ignition-type internal combustion engine.
It is an object of the present invention to at least overcome the above-described drawbacks of the related art.
It is also an object of the present invention to provide a vehicle wherein a reformed liquid fuel containing a large amount of a component having a high octane value is produced to enhance the energy efficiency of an internal combustion engine.
To achieve the above objects, according to the present invention, there is provided a vehicle that is provided with an internal combustion engine and that performs fuel-reforming/supplying functions. The internal combustion engine includes a reformer that reforms at least a portion of liquid fuel using a dehydrogenating cyclization reaction to produce a reformed liquid fuel, that is rich with aromatic hydrocarbon and has a high octane value, as well as a reformed gaseous fuel that is rich with hydrogen. The internal combustion engine also includes a gas-liquid separator that separates the reformed liquid fuel and the reformed gaseous fuel from each other, and a device to supply at least a portion of the reformed liquid fuel as a fuel to the internal combustion engine.
The dehydrogenating cyclization reaction produces a reformed liquid fuel that is rich with aromatic hydrocarbon and has a high octane value from the liquid fuel containing a hydrocarbon with a low octane value, thereby enhancing the energy efficiency of the internal combustion engine.
It is another object of the present invention to provide a vehicle with a stabilized reforming reaction.
To achieve this object, according to the present invention, there is provided a vehicle that is provided with an internal combustion engine and that performs fuel-reforming/supplying functions. The internal combustion engine includes a device that supplies at least a portion of the reformed gaseous fuel to a burning-type heater of the reformer.
While producing the aromatic hydrocarbon, a reformed gaseous fuel that is rich with hydrogen is also produced. The reformed gaseous fuel is separated from the reformed liquid fuel, and at least a portion thereof supplied as a fuel to the heating gas burning-type heater of the reformer. Therefore, the reforming reaction in the reformer is stabilized.
It is yet another object of the present invention to provide a vehicle having a high energy efficient internal combustion engine and fuel cell.
To achieve this object, according to the present invention, there is provided a vehicle that is provided with an internal combustion engine and a fuel cell, and that performs fuel-reforming/supplying functions. The internal combustion engine includes a reformer that reforms at least a portion of a liquid fuel using a dehydrogenating cyclization reaction to produce a reformed fuel, that is rich with aromatic hydrocarbon and has a high octane value, as well as produces hydrogen. The internal combustion engine also includes a hydrogen separator that separates hydrogen from the reformed fuel, a device to supply at least a portion of the reformed fuel as a fuel to the internal combustion engine. The engine also includes a device to supply the separated hydrogen as a fuel to the fuel cell.
The dehydrogenating cyclization reaction is generated at a relatively low temperature from 400 to 700xc2x0 C. and hence, it is possible to simplify the reformer. Because no carbon monoxide is produced during the dehydrogenating cyclization reaction, a carbon monoxide-removing device is not required to supply the produced hydrogen as the fuel to the fuel cell. The energy efficiency of the internal combustion engine is enhanced by using, as a fuel for the internal combustion engine, the concurrently-produced reformed fuel that is rich with aromatic hydrocarbon and contains a component having a high octane value.
It is a further object of the present invention to provide a vehicle wherein the ignition timing is promptly controlled in response to the operational state of a premixing and compression/ignition-type internal combustion engine.
To achieve this object, according to the present invention, there is provided a vehicle which performs fuel-reforming/supplying functions and includes a premixing and compression/ignition-type internal combustion engine in which a mixture has an oxygen-containing gas and a fuel that is compressed and self-ignited, a device to supply a liquid fuel which is not reformed to the premixing and compression/ignition-type internal combustion engine, a reformer to reform the liquid fuel using a dehydrogenating cyclization reaction to produce a liquid fuel that is rich with aromatic hydrocarbon and has a high octane value, and a device to supply the liquid fuel having the high octane value as a fuel to the premixing and compression/ignition-type internal combustion engine.
With the reformer, liquid fuels having different combustibilities are produced in the vehicle, and the liquid fuel resulting from the reforming as well as the liquid fuel before being reformed are supplied at any proportion to the premixing and compression/ignition-type internal combustion engine. Therefore, the proportion of the two liquid fuels to be supplied can be promptly changed in response to the operational state of the premixing and compression/ignition-type internal combustion engine in order to control the ignition timing of the premixing and compression/ignition-type internal combustion engine.